The importance of nucleoside 5'-di-and triphosphates for the synthetic processes of the cell has led to the development of numerous chemical (l-3) and enzymic (47) methods for their preparation. Although these methods have obvious advantages, each is subject to limitations.
Thus, the chemical procedures are inefficient when mpmole or even pmole quantities of nucIeotide are required, whereas the enzymic methods often require extensive purification or facilities to grow and harvest bacteria. We, therefore, would like to present another method which may in some instances supersede the previously described procedures.
These studies were the outgrowth of an investigation of the levels of deoxycytidylate deaminase in regenerating liver (8, 9), where it was found that the employment of heat denaturation to terminate reactions containing dCMP-2-Cl4 yielded higher zero time blank values than did reactions terminated with acid.4 Further investigation revealed the elevated blanks to be due to the presence of dCDP and dCTP, products apparently resulting from the presence of heat-stable phosphotransferases in the liver extracts. Subsequent study indicated that, in addition to dCMP, all of the naturally occurring nucleotides except dTMP were converted to nucleoside di-and triphosphates in heated liver extracts.